ANSWER: The minimum percentage is 10%.EXPLANATION: For simplicity, let's say there are 100 students at the school. This would
mean 60 students are girls and 40 are boys. 70 students would have green eyes and at most 40 of those
could be boys. So at a minimum, there are 30 girls with green eyes. 80 students have blonde hair so 20
students have non-blonde hair. Of the minimum 30 girls with green eyes, at most 20 of those could have
non-blonde hair. So at a minimum, there are 10 girls with green eyes and blonde hair, or 10% of the 100
students.

Do you have a suggestion for this puzzle (e.g. something that should
be mentioned/clarified in the question or solution, bug, typo, etc.)?